Cytomegalovirus (CMV) infection is a common complication of renal, liver, and cardiac allograft transplantation. The morbidity of this infection may be related to an ability of CMV to facilitate allograft rejection. The proposed studies are based upon the central hypothesis that active CMV infection of allograft endothelial cells results in upregulation of their cytokine-inducible immune inflammatory properties, with subsequent facilitation of allograft rejection. Thus, the long term objectives of this research program are to investigate the effects of CMV infection on human endothelial cell immunobiology, particularly baseline and cytokine-inducible immune inflammatory properties. The specific aims of this study are as follows: I. To further characterize infection of cultured human endothelial cells (ECs) by nonattenuated (clinical) CMV isolates. These experiments will test the hypothesis that clinical isolates are more ineffective than laboratory strains, particularly in nonconfluent cultures, as verified by detection of viral antigens, viral DNA, and a fibroblast plaque-forming assay. These experiments will provide a firm basis for the remaining specific aims. II. To characterize the effect of CMV infection on endothelial cell HLA Class I and II antigen expression. These experiments will test the hypothesis that CMV infection of ECs upregulates baseline, gamma interferon (IFN-y), and tumor necrosis factor (TNF)-induced, HLA Class I and class II antigen expression. These experiments will utilize immunohistochemistry, Cell-ELISA, and flow cytometry. III. To characterize the effect of CMV infection on endothelial cell interleukin-1 (IL-1) synthesis. These experiments will test the hypothesis that CMV infection of ECs upregulates baseline and TNF-induced IL-1 synthesis, as assessed by an immunohistochemical assay, Cell-ELISA, and flow cytometry. IV. To characterize the effect of CMV infection on endothelial adhesion for T lymphocytes. These experiments will test the hypothesis that CMV infection of ECs upregulates baseline, TNF, and IFN-y-inducible adhesion. Operative receptor/ligand molecules will be studied by inhibition with monoclonal antibodies to adhesion molecules.